Grafting of flax fiber (Linum usitatissimum) with vinyl monomers for enhancement of properties of flax-phenolic composites

Binary vinyl monomers such as methylmethacrylate (MMA)/Ethylacrylate (EA), MMA/Acrylonitrile (AN) and MMA/Acrylic acid (AA) have been graft co-polymerized onto flax fibers under the influence of microwave radiations (MWR). Various reaction parameters have been optimized and maximum grafting (25%) was observed in reaction time of 30 min at 210 W microwave power. Flax-g-copolymers thus prepared were used as reinforcing material in the preparation of flax-phenolic composites. Wear resistance was maximum with reinforcement of Flax-g-poly(MMA/AA). Composites reinforced with Flax-g-poly(MMA/EA) showed better tensile strength and can bear load upto 225 N with extension of 3.28 mm and composites reinforced with Flax-g-poly(MMA/AA) showed better compressive strength and can bear load upto 1000N with compression of 1.74mm. Maximum values of MOR, MOE and SP were found to be 108.0 N/mm(2), 5295.62 N/mm(2) and 99.29 N/mm(2) for the composites reinforced with Flax-g-poly(MMA/AA). On grafting of flax fibers with vinyl monomers, fibers become more and more moisture retardant. It has been found that strength of Flax-g-copolymers was found more than that of raw flax fibers. Flax-g-poly(MMA/ AA) has been found to show good thermal stability in comparison to other graft co-polymers and raw flax fibers. Phenol-formaldehyde (PF) composites reinforced with graft co-polymers of flax fibers showed better mechanical properties in comparison to composites reinforced with raw flax fibers. Composites reinforced with Flax-g-poly(MMA/AA) showed the increased values of MOR, MOE and SP.